Fluid drive fob compressors



March 27, 1945. E. EHEWITT 2,372,326

FLUID DRIVE FOR COMPRESSORS Filed June 30, 1943 INVENTOR ELLIS EHEWITT BYaic:

ATTORNEY Patent ed Mar. 27, 1945 UNITED STATES PATENT OFFICE FLUID nnrvn FOR oomasssons smea -mam, Edgewood, as" assign to Westinghouse Ali-Brake Company, Wilmerding,

rat, acorporation of Pennsylvania; Application-June so, 1943, Serial no.- 492,793:

3 Claims.

This invention relates to'fluld power transmis sion equipment, and particularly to a fluid drive apparatus operable by a. variable speed engineto drive:' and control operation. of a compressor'or other device.

In atransportation service in which a Dieselelectric powerequipmentis employed, it has been proposed to utilize a portion of the mechanical energy developed by the engine to effect direct operation of anassociated compressor, thereby saving the expense and waste of a separate driving motor; Because of the varyingspeed at which the Diesel engine is generally operated, however, it isdesirable to provide for transmis-' sion' of power therefrom to the compressor speed by a driving member the speed of which may vary. p

It is another object of my invention-to adapt. a well known type of fluid drive, apparatus for directly transmitting power from a fliesel electric assembly to a compressor of the class described,

by associating therewith an automatic fluid pressure controlling system of novel construction Another object 01' the invention-is to provide an improved fluid power transmission equipment-in eluding fluid pressure-meanslrespensiv w tion of the engine for insurinroperation of-"the compressor at a relatively constant speed}. and

governor means for also controlling the compressor in accordance with receiving" reservoir Diesel-electric power unit and a compressor for driving the latter at aselected normal speedd'uring operation of the engine at aslow or idling speed; and including control meansfor preventme operation of the compressor at excessive-speed when the engine is driven at a taster'rate'i Still another object is to pidvide' acompressor governor adapted to cooperate with ailnid drive system for starting and stopping" thecompressor in accordance with the pressure of fluid compressed thereby.

In the drawing, the single figureis a, disarm mati'c view of a compressor and fluid power transshown'in section, it beingaunderstood that certainparts of the assembly are. shown in reduced size,

Referring tothe drawing, the apparatus illustrated comprises. a compressor l0 operative to supply fluid under pressure to a reservoir H, a Diesel'engine- I2-,.a generator 13 operatively connected thereto, ahydraulic torque converter or couplingdevice H for transmitting power from the engine to the compressor, a compressor governor device I6, a control valve device I1, and a-motor driven pump I 8.

The hydraulic power coupling device l4 comprises a rotary impeller 22, which is secured by means ofia key 23 to a driving shaft 24 which, in the present embodimentof the invention, is associated with both the Diesel engine i2 and gener skirt portions or shells 34 and 35, which are adapted-to extend over the runner for containing the hydraulic fiuid that is introduced between the two rotary elements, as hereinafter explained.

The impeller 42 is provided with a plurality of semi-circular cavities 38 whichare arranged radially therein and open into 'a chamber 40 intermediate. the impeller and runner by way of inlet ports I and outlet ports 42. It will be observed that theinlet ports 4! of the cavities 38 are disposed" at a-smaller radial distance from the axis of the impeller than are theoutlet ports 42.

The runner 25 is adj d'f'to-Bbe driven by hydraulic fluid thrown; 1mm th 'impeller and is similarly provided"with-semi-circular cavities 43 into theintefinediate chamber 40 by way of" outer and inner Land 50, which are arranged in concentricralig-nment with the ports 42'and- 4|, respectively. The hub of the runner 25 hasrformed therein an annular cavity 52 communicating by way of supply ports-53 with the chamber 40. Also communicating with the annular cavity 52- in the runner are an inlet passage 55 formed in the casing structure 32, and an outlet passage 55 whichin turn communicates with a= drain chamber 51 formed in the lower portion of the casing. structure. A pick-up tube is semissi'o'n equipmentg-with eemmeiem mm: ll cured to the casing structure adjacent the outlet passage 56, and extends downwardly between the inner and outer shells 84 and 35.. This tube is adapted to carry to the passage 56 some of the hydraulic fluid that travels at high velocity within the space 36 between the rotating shells, during operation of the device as hereinafter explained. Communication between the chamber 40 intermediate the impeller and runner and the space 36 is maintained through the medium of a plurality of leakofi nozzles 62, which are formed in the peripheral portion 33 of the impeller.

The compressor governor device I6 comprises a casing structure 10 having a bore1-li'in 'which I is slidably mounted a piston, 12, which is operatively connected through the medium of a stem' 13 with a valve element 15 that is disposed with- I in a valve chamber 16. The valve element 15 is normally held in engagement with a seat' 11 formed on the casing structure, under the force exerted by a coil spring 18, while the piston 12 is normally maintained in its uppermost position as shownin the drawing under the force of a coil spring 80, which is interposed between the piston and awall I .formed within the casing structure. The bore H is connected throu h a pipe 83 with the reservoir II, sothat the piston 12 is subject to the pressure offluid in the reservoir in opposition to -the combined forces of springs 18 and80. The valve elementu15 is adapted "to control communication from the chamber 16 to a chamber 84, which is :formed in the casing structure and communicates by way of a conduit 88 and an assembly of cooling tubes 81 with the drain-chamber 51 of the fluid coupler device I 4., The valve chamber 15 is at all times in communicationthrougha pipe 80 with the inlet passage55 of the fluid coupler device.

The chamber 84 of the governor device I6 also communicates byway of .a pipe 9| with the sump eration to control circulation of hydraulic fluid through the fluid coupling device I4 in accordance with the speed at which the generator I3 is driven by the engine I2. This 'device'comprises a casing structure I00 having 'an inlet passage lfll communicating with the pipe an outlet pastails of the electrical connections need not be described in detail, it will be understood that the magnet coil H2 is constructed and arranged to be energized to a degree that is a measure of the speed at which the generator I3 is operated by the engine I2, and that the core member III of the control valve device I1 is thereby subjected to a variableupward pull in opposition to the force exerted by'the spring I08.

' When the equipment is in condition for operation, the pump I8 is adapted to be driven by mo tor 81 to supply hydraulic fluid from the sump 02 to. the chamber 40 of the hydraulic coupling device I4 by way of pipe 98, valve chamber in govsage I03 communicating with thepipe 0|, and

an intervening'bore containing'a valve plunger I05 that isadapt'ed to establish communication between the passages IM and I03 through one .or more ports I00 formed in the walls of the'bore.

A coil spring I08 is interposed between-- the plunger valve I05 and an upper wall I09 of the casing structure, and is normally effective to hold the plunger valve in its lowermost position, as shown in the drawing, for thereby closing all of the ports I06. The plunger-valve has *a stem I I0 which extends upwardly through an aperture in the wall I00 and isconnected to a. core member I II that is operativelyassociated with amagnet coil I I2 suitably mounted on the casing structure. The coil H2 is arranged for energization through the medium of suitable conductors I I3 leading to the generator I3. Althoughthe de- I ernordegvice l'fi, pipe 89, and inlet passage 55, while jhydraulic fluid is-ifree to flow back to the sump 02 of thepump through theoutlet passage 55, "drain chamber 51, cooling tube assembly 81, pipe 86, chamber 84 in the governor device, and pipe 9|. Upon operation of the generator I3 by the Diesel engine I2, the shaft 24 and impeller 22 are rotatedrelative to the initially stationary runner 25, with theresult that hydraulic fluid is drawn from the chamber through the radial cavities 38 and ejected at an accelerated velocity from the outer'ports 42of the impeller. The hydraulic fluid is' thereby thrown tangentially against the vane surfaces of the runner 25between the cavities 48 therein, and as it flows inwardly through the cavities exerts a torque against the runner 25 causing rotation thereof with the impeller 22.

Circulation of the hydraulic fluid through the ,It willbe understood that'the'quantity of hydraulicfluid circulating through the cavities in theimpeller and runner elements determines the ratio of the runner speed to the impeller speed, and consequently the relative speed at which the co'mpressorI0-is driven by the Diesel engine I2. In other words, the speed of the compressor may be expected to approach that of the Diesel engine when the quantilty of hydraulic fluid available for circulation through the hydraulic 'coupling device I4 isincreased, while on the other hand a withdrawal ofjhydraulic fluid from the hydraulic couplirignevice will result in reduction in the speed of the compressor relative to that of the engine. v

Assuming that the illustrated equipment is carried on a railway locomotive, the hydraulic coupling device and the associated controlling apparatus are preferably constructed and arranged to effect operation of the compressor In at about the normal maximum speed for which it is designed, so long-as the Diesel engine I2 rotates the drive shaft 24 at an idling speed. 'Under this operating condition, the maximum quantity of hydraulic fluid is circulated through the hydraulic coupling device I4 for causing the runner 25 to be driven by the impeller 22 with a minimum slip or speed difierential, as will be apparent from the foregoing description. When the Diesel engine I2 is thus operated to drive the generator I3 at an idling-speed, the output of the generator, as measured by the extent of energization of magnet coil II2 of the control valve device I1, is too low to cause operation of the valve plunger I 05,, so thattheelement is held in the normal position, as shown, under the force of the spring I08. Assuming that the pressure of fluid in the reservoir II remains below that required to cause operation of the governor device I6, and that the valve element I is likewise held in its normal seated position, the entire output of hydraulic fluid is thus delivered from the motor driven pump I8 to the hydraulic coupling device I4.

, When the Diesel engine I2 is subsequently operated at a higher speed, thus increasing the output of the generator I3 as well as the rotative speed of the shaft 24 and impeller 22, the resultant increase in energization of the magnet coil II2 of the control valve device I! causes upward movement of the core member I I I, stem III), and valve plunger I05, in opposition to the force of spring I08. In so moving, the valve plunger I05 uncovers one or more of the ports I06 and thereby establishes communication between the pipes 98- and SI, through which a portion of the hydraulic fluid discharged by pump I8 flows back to the sump 92. The quantity of hydraulic fluid which continues to flow on through the pipe 98; valve chamber I6, and pipe 89 to the hydraulic coupling device I4 is thus reduced sufliciently to cause a lag in the rotative speed of the runner with respect to the speed of the impeller 22. Assuming that the various operating elements of the equipment have been properly proportioned and designed, it will be understood that although the impeller 22 of the hydraulic coupling device is now driven at a higher speed than that corresponding to the idling speed of the engine I2, the runner 25 is nevertheless operated to drive the compressor ID at substantially the normal speed by reason of the reduction in the driving ratio, in the manner just explained.

The compressor governor device It is operative independently of the control valve device IT, in accordance with variations in the pressure of fluid supplied to the reservoir II by the compressor Ill. Upon an increase in reservoir pressure to the value to which the governor device I6 is designed to respond for unloading the compressor, the piston I2 is forced downwardly against the spring 80 and acts through the medium of the stem 13 to move the valve element I5 away from seat II. A wide open communication is thereby established through which hydraulic fluid is free to flow from the valve chamber I5 through chamber 84 and pipe 9i tov the sump 92, so that substantially all of the fluid is diverted from the communication leading to the hydraulic coupling device I4. As' hydraulic fluid is consequently withdrawn from the coupling device, the runner 25 and shaft 21 cease to revolve with the impeller 22, and the compressor Ill becomes inoperative.

When the pressure of fluid in the reservoir II falls below the pressure for which the governor device It is set, the spring 80 becomes effective to shift piston I2, stem 13, and valve element I5 upwardly until the valve element again closes communication between the chambers I6 and 84. Continued operation of the pump I8 is then effective to restore the circulation of hydraulic fluid through the hydraulic coupling device I 4,

and the compressor II) will again be set in operation in the manner hereinbefore explained.

It will thus be seen that a fluid drive c0ntr0lling apparatus embodying the features of the invention just described and arranged for coupling a Diesel electric power equipment with a compressor, will be automatically operative at all times to eflect operation of the compressor at a substantially constant speed regardless of variations in the driving engine speed, and also to govern operation of the compressor in accordance with the fluid pressure in the receiving reservoir.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is: 1

1. In a hydraulic drive and control apparatus constructed and arranged for coupling a variable speed engine to a compressor, in combination, a hydraulic coupling device operable by said engine to drive said compressor at a rate determined by the circulation of fluid therein, a generator driven by said engine, pump means operable to deliver a constant supply of fluid, and electrorespo-nsive valve means energized in accordance with operation of said generator for controlling the flow of fluid from said pump means to said coupling device.

2. In a hydraulic drive and control equipment constructed and arranged for coupling a variable speed engine to a compressor, in combination, a fluid torque converter operable in accordance with circulation of fluid therein to transmit torque from said engine to said compressor, a constant speed pump having a sump reservoir associated therewith, pressure communication means through which said pump is adapted to supply fluid under pressure to said torque converter, drain communication means for conducting return flow of fluid from said torque converter to said sump reservoir, and control valve means operable to establish a by-pass communication between said pressure communication means and said drain communication means.

3. In a hydraulic drive and control equipment constructed and arranged for coupling a variable speed engine to a compressor, in combination, a fluid torque converter operable in accordance with circulation of fluid therein to transmit torque from said engine to said compressor, a

. constant speed pump having a sump reservoir 

